readb() and writeb() would help to access serial device
via MMIO address space.
Signed-off-by: Andy Shevchenko <andriy.shevche...@linux.intel.com>
---
arch/x86/boot/boot.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index 7e6ac187275c..09f6829f2778 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -79,6 +79,18 @@ static inline void io_delay(void)
asm volatile("outb %%al,%0" : : "dN" (DELAY_PORT));
}
+static inline u8 readb(const volatile void __iomem *addr)
+{
+ u8 v;
+ asm volatile("movb %1,%0" : "=q" (v) : "m" (*(volatile u8 __force
*)addr));
+ return v;
+}
+
+static inline void writeb(u8 v, volatile void __iomem *addr)
+{
+ asm volatile("movb %0,%1" : : "q" (v), "m" (*(volatile u8 __force
*)addr));
+}
+
/* These functions are used to reference data in other segments. */
static inline u16 ds(void)
--
2.15.1
